Figure 4.

Control correction of each spot markedly improves the distribution of log ratios. (A) Histograms show that T/C and C/C log ratio distributions after lowess normalization still have a marked asymmetry with a larger tail towards the left (increased down-regulated genes). The distribution becomes symmetric after subtracting the log (C/C) from the log (T/C). (B) Quantile-quantile plots similarly show that the log ratio distribution becomes more normal after correction of each spot with the control ratio.